An official [from the International Atomic Energy Agency] familiar with the matter, who asked for anonymity because he was not authorized to comment, said the release appeared to be continuing.

Some scientists have made some unlikely claims about the source of the radiation. For example, as Reuters notes:

Professor Malcolm Sperrin, director of medical physics at Britain’s Royal Berkshire Hospital, said any link with Fukushima was extremely unlikely.

“It is far more likely that the iodine may be as a result of excretion by patients undergoing medical treatment. Whilst such patients are carefully controlled, some release of iodine into the environment may be inevitable but would certainly be well below any limits where health detriment would even begin to be an issue for concern,” he said.

(It is unlikely that patients in so many countries would all start excreting more radioactive iodine at the same time.)

The Czechs deny responsibility, but are sending mixed signals. As AP notes:

In Prague, an official at the Czech State Office for Nuclear Safety said he was “100 percent sure” that the radiation had not come from any Czech nuclear power plant — or from any other source on Czech territory.

[However,] speaking on condition of anonymity because he wasn’t authorized to talk to the media, the official said tests are under way around the country to try and identify the source.

The Czechs are betting heavily on nuclear power and have plans to dramatically increase production ….